What's the "pre" in presale about if anyone is permitted to buy in it? The more restrictive it is, the better (only huge ammounts, not marketed/secretive etc.) but today they are just marketing props
It's a marketing ploy, but it's not so different than early seed money in venture capital. Generally, the earliest angel investors in a startup get a much larger share of the company than later investors. And this makes perfect sense, doesn't it? They are taking the most risk. It's like Series A vs. Series B funding. Once you get to the later rounds of funding, it's clear that the business model is viable and investor demand is much higher. Price is therefore higher.
It's definitely riskier investing in an ICO that has raised $0 than an ICO that has raised $50 million. That's what justifies the pre-ICO vs. ICO price.